The present invention relates to a fan motor employed for cooling an electronic device or the like.
Japanese Patent Application Laid-Open Publication No. 191611/1998 discloses a fan motor including a cup-like member and an impeller. The cup-like member has a cylindrical section with a plurality of rotor magnetic poles on an inner peripheral side thereof and a bottom wall section that blocks one end of the cylindrical section. The impeller includes a plurality of blades arranged outside the cylindrical section. In the fan motor of this type, in order to increase the volume of airflow and static pressure performance to aim at its higher performance, input power to windings is increased. The number of revolutions of the motor is thereby increased.
However, if the number of revolutions of the motor is increased as described above, the amount of heat generated in the windings increases. Then, when this heat generation causes the heat to be transferred to the bearings of the motor and the temperature of the bearings thus increases, the life of the bearings is reduced. For this reason, because of the need for suppressing the increase in the temperature of the bearings, the higher performance of the fan motor was conventionally hindered.